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• Rational Rose Real Time Presentation

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• Real-Time System Design Concepts

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• Characteristics of Real-Time Systems– Responsiveness– Timeliness– Concurrency– Dynamic structure and behaviour– Distribution– Reliability

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• Hard Real-Time Systems– Deterministic system behaviour

• Soft Real-Time Systems

• System combinations of Soft and Hard Real-Time Systems

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• Hard Real-Time Systems are often designed with an additional component that is not part of the UML Standard – Timing Diagrams.

Hard Real-Time Systems are often designed to interact with sensors and activators on the equipment that the system is communicating with.

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• Hard real-time systems that are safety-critical may contain within the architecture a watchdog timer implementation.

• Watchdog timers may be built into a microprocessor card and are typically driven by a periodic reset signal from the primary processor. If the reset signal fails to reset the watchdog timer within that time, the watchdog timer restarts the main processor.

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• Real-time systems may make use of a technique called “interrupts”.

Interrupts may be disabled and the result is a portion of code that is “atomic”. Some portions of a real-time system to operate correctly are labelled “critical sections” are must be atomic for the system to operate properly.

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• Modeling Real-Time Systems

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• Concurrency support from operating systems and programming languages is limited.

• Many complex real-time systems are state-based. The behaviour of these systems may be difficult to design and understand.

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• In order to model states with concurrency one needs a notation, a process and a tool.

• This pyramid of building blocks is represented by the Unified Modeling Language, the Rational Unified Process and the Rational Rose Real-Time Modeling tool.

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• UML and Rose Realtime handle concurrency with the capsule. The capsule provides this capability to model concurrency.

• To support concurrency a passive object must exercise control over “critical” or “atomic” sections of code where variable could be accessed simultaneously. An example of the problem is the Shared Data Bug.

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• Active Objects and Finite State Machines– State – condition in which an active object

persists and behaves in a predetermined way for some time

– Transition -- path connecting two states – Trigger – an event which fires a transition– Action – work performed by action code when

transition is fired by the triggering event

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• Capsule enforce the O-O concept of encapsulation.

• Capsules interact via asynchronous message passing.

• Capsules encapsulate the finite state machine behaviour, an execution thread, and the properties of the capsule.

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• Capsules may be concurrent or distributed.• Capsules may be tested independently.• Demonstrate use of a capsule in a concurrent

architecture.• In a Class Diagram identify the UML notation for a

capsule. – Attributes– Operations– Ports– Finite State Machine– Structure Diagram

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• UML Models– Use Case Model – similar to requirements– Design Model – realized by class diagrams– Implementation Model – collection of

components– Test Model – test cases and procedures

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• Rose Real-Time Views– Use-Case View – use-case diagrams; interaction diagrams –

sequence and collaboration diagrams; – Logical View – class diagrams; structure diagrams; state

diagrams; collaboration diagrams; sequence diagrams;– Implementation (Component) View – executables, C++

Libraries; C++ External Libraries – Deployment View – software components are mapped to

hardware deployment configuration– See Rational Training Course DEV160 Modeling Behaviour

with UML– Demonstrate the views to the working group.

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• Use-Case View diagrams consist of use-case and interaction diagrams

• Use Case Diagrams consist of actors and use cases

• Actors are outside of the system and interact with the system

• Use cases are actions performed by the system

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• Interaction Diagrams consist of collaboration diagrams– Framework for sequence diagrams

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• Sequence Diagrams are interactions between elements as a time ordered set of messages.

• Contain instances of capsules.

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• Logical View contains Class Diagrams, Structure Diagrams, State Diagrams, Collaboration Diagrams and Sequence Diagrams.

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• Class Diagrams depict static view of Packages, Capsules, Classes, Protocols and Relationships

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• Structure Diagrams are a specialized Collaboration Diagram.

• Contain Capsule roles, Ports and Connectors.

• Structure diagrams are contained within a capsule.

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• State Diagrams depict high level behaviour of a capsule in a finite state machine

• Contain States, substates and transitions

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• Component View describes organization of static software modules

• The software is built in this view (i.e. compiled)

• Contains executables and C and C++ Libraries

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• Deployment View is where software components are mapped onto hardware

• Contains processors and component instances– Processors describe on what processor the built

component is run on– Component instances are executable

components

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• Socket Interface Presentation• The purpose of this presentation is to describe how a Socket Interface may be implemented using Rational Rose.

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• This demo uses the following Architecture:

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• This is the Class Diagram for the server (ReceiverSameThread) and client (SenderSameThread) capsules. They represent the top-level capsules for the ping/pong example. The IPC and TCP capsules are incarnated by the top-level capsules onto a physical thread configured with the RTCustomController implementation class.

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• The Class Diagram depicts a composition relationship between the top-level capsules and the IPC and TCP capsules. The next two slides describe a composition relationship.

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• Server Side Socket Connection

Description

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• The IPCReceiver capsule is incarnated by the top-level capsules onto a physical thread configured with the RTCustomController implementation class i.e. a RTCustomController thread.

• The frame service in Rose Real-Time is used to incarnate an IPCReceiver capsule role.

Baltimore SIGAda• An example of how the frame service is used below to incarnate (i.e. create or instanstiate) capsule roles, destroy capsule roles, plug in capsule roles (i.e. import) or unplug capsule roles (i.e. deport)

• id = frame.incarnate(iPCReceiver, IPCReceiver, EmptyObject, CustomIPCThread );

Baltimore SIGAda The frame service call is action code contained within the transition Labelled initialize. This is a state diagram for the capsule ReceiverSameThread.

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• The incarnated TCPServer and TCPClient architecture

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• Here is structure diagram which contains a capsule role labelled iPCReceiver.

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• The previous slides shows a structure diagram for ReceiverSameThread which contains a capsule role labelled IPCReceiver. This capsule role has a symbol in the lower right corner that indicates that there is a nested capsule role within this capsule role.

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• The structure diagram for IPCReceiver capsule contains a capsule role labelled customIPCLayer of class TCPServer.

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• iPCReceiver refers to the optional Capsule Role

• IPCReceiver is the address to myData

• EmptyObject is an optional piece of data that is delivered to the capsule in its initial transition.

• CustomIPCThread refers to the logical thread in which the capsule runs on.

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• The IPCReceiver capsule controls the number of messages exchanged with the TCPclient capsule through the contained optional capsule 'customIPCLayer'.

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• The capsule role labelled customIPCLayer of class TCPServer is connected via a connector to a port labelled talkRemote.

• The talkRemote port is a conjugated, wired, protected, end port in the structure diagram for IPCReceiver.

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• In the previous slide, the rounded rectangle attached to the end port refers to the state machine of the associated capsule. So messages coming in on this port are delivered to, and are processed by the associated capsule’s state machine. The connected boxes inside the rounded rectangle refer to a connection. Ports that have the connected boxes in it are wired ports.

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• This is the state diagram for the IPCReceiver capsule.

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• The following slide depicts how action code contained within the transition labelled Initialize will incarnate a TCPServer.

Baltimore SIGAda• An example of how the frame service is used below to incarnate (i.e. create or instanstiate) capsule roles, destroy capsule roles, plug in capsule roles (i.e. import) or unplug capsule roles (i.e. deport)

• id = frame.incarnate(customIPCLayer,

TCPServer, EmptyObject, CustomIPCThread );

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• The action code in the transition labelled ping uses the talkRemote port to send the pong signal. The format for sending data in Rose Real-Time is port_name.signal(data).send();

• The pong signal is defined in a protocol class and optionally may have data associated with them. Action code is below.

• talkRemote.pong().send();

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• This is the state diagram for the TCPServer capsule.

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• The transition for internalSetup sets a variable called internalFd which will be used by 'wakeup' calls to unblock the RTCustomController.

• internalFD is a internal UDP socket descriptor.

• UDP sockets are connectionless and have no protocol. There are suitable to use for the purpose of local host (board) communication.

• internalFd = makeUdpConnection();

Baltimore SIGAda• A connectionless service is one in which transmissions take place without a pre-established path between the source and destination. Because packets may arrive by different paths and in random sequences, there is no way to guarantee delivery of a message in a connectionless service. Because it can not guarantee delivery, a connectionless service is described as a best effort service.

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• The Action Code for the choice point labelled internalOK checks the value of internalFd [which is an internal socket descriptor] to see if if it has been set to a value other than -1 which it was initialized to.

• Action code is on next slide.

Baltimore SIGAda• if( internalFd < 0 )• return 0; // not OK• // Follow the FALSE path

• // of the Choice Point

• ioMonitor.add( internalFd, RTIOMonitor::CanRead );

• return 1; // OK• // Follow the TRUE path

• // of the Choice Point

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• TCPServer side transition action code for externalSetUp on next three slides

• create an variable labelled listener of type RTTcpSocket class

• RTTcpSocket listener;

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• use the RoseRT log service to output a message

without a carriage return and the integer value of the listening port.

• LISTENING_PORT is a constant in the TCPIP_Proxies package and its value is set to 31736

• log.show("Listening to: "); log.log( (int)LISTENING_PORT );

Baltimore SIGAda• ioMonitor of class RTIOmonitor is used to monitor the external socket channel 'c_socket'

• registerWith is a public function which returns a void which is contained within header file RTTcpSocket.h

• c_socket.registerWith( &ioMonitor );

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• Action Code for Choice Point labelled external OK

• The function int RTTcpSocket::state() returns 'Established‘ if the socket file descriptor is usable

• return ( c_socket.state() == RTTcpSocket::Established );

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• if the state() function returns Established then the socket file descriptor is usable then take the TRUE path of the choice point which in this case is registerWithController

• if the state() function does not return Established then the socket file descriptor is not usable then take the FALSE path of the choice point which in this case is giveUP

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• Action Code for transition labelled giveUp

• Use the Rational Rose RT System Service called the Log Service to output a message without a carriage return

• log.show("IPC channel initialization failed\n");

• Close the external socket channel c_socket

• c_socket.close();

Baltimore SIGAda• Action Code for transition labelled registerWithController

• The macro REGISTER_LAYER takes three arguments which are pointers to the 'waitfunc', 'wakeupFunc', and 'processFunc‘ functions to be called by the RTCustomController.

• If any of these are null pointers the default values are used.

• The waitForEvents function is called when the when the RTCustomController does not have any messages left to deliver.

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• REGISTER_LAYER( waitForEvents, wakeup, 0);

• Use the Rational Rose RT System Service called the Log Service to output a message with a carriage return

• log.log("Connected");• set the length of the buffer to the integer value of the constant BUFFLEN which is in this 100

• buffLen = (int)BUFF_LEN;

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• State Diagram for substate labelled Operational

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• Action Code for transition labelled ‘pong’

• int RTTcpSocket::write() - writes on a socket file descriptor using the system call write

• The incoming buffer needs to be of size buffLen which is 100

• if( c_socket.write( incomingBuffer, buffLen ) != buffLen )

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Use the Rational Rose RT System Servic called the Log Service to output a message without a carriage return

• log.show( "TCPServer: incomplete write\n" );

• the incoming Buffer was not of length buffLen

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• This is the structure diagram for the TCPServer capsule.

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• The port labelled talkRemote is an public, unconjugated, wired end port.

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• Client Side Socket Description

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• The incarnated TCPServer and TCPClient architecture

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• The IPCSender capsule is incarnated by the top-level capsules onto a physical thread configured with the RTCustomController implementation class i.e. a RTCustomController thread.

• The frame service in Rose Real-Time is used to incarnate an IPCSender capsule role.

Baltimore SIGAda• An example of how the frame service is used below to incarnate (i.e. create or instanstiate) capsule roles, destroy capsule roles, plug in capsule roles (i.e. import) or unplug capsule roles (i.e. deport)

• id = frame.incarnate(iPCSender, IPCSender, EmptyObject, CustomIPCThread );

Baltimore SIGAda The frame service call is action code contained within the transition Labelled initialize.

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• Here is a structure diagram which contains a capsule role labelled iPCSender.

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• The previous slides shows a structure diagram for SenderSameThread which contains a capsule role labelled IPCSender. This capsule role has a symbol in the lower right corner that indicates that there is a nested capsule role within this capsule role.

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• The structure diagram for IPCSender capsule contains a capsule role labelled customIPCLayer of class TCPClient.

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• iPCSender refers to the optional Capsule Role

• IPCSender is the address to myData • EmptyObject is an optional piece of data that is delivered to the capsule in its initial transition.

• CustomIPCThread refers to the logical thread in which the capsule runs on.

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• The IPCSender capsule controls the number of messages exchanged with the TCPServer capsule through the contained optional capsule 'customIPCLayer'.

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• The capsule role labelled customIPCLayer of class TCPServer is connected via a connector to a port labelled talkRemote.

• The talkRemote port is an unconjugated, wired, protected, end port in the structure diagram for IPCSender.

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• In the previous slide, the rounded rectangle attached to the end port refers to the state machine of the associated capsule. So messages coming in on this port are delivered to, and are processed by the associated capsule’s state machine. The connected boxes inside the rounded rectangle refer to a connection. Ports that have the connected boxes in it are wired ports.

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• This is the state diagram for the IPCSender capsule.

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• The following slide depicts how action code contained within the transition labelled Initialize will incarnate a TCPClient.

Baltimore SIGAda• An example of how the frame service is used below to incarnate (i.e. create or instanstiate) capsule roles, destroy capsule roles, plug in capsule roles (i.e. import) or unplug capsule roles (i.e. deport)

• id = frame.incarnate(customIPCLayer,

TCPClient, EmptyObject, CustomIPCThread );

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• The action code in the transition labelled pong uses the talkRemote port to send the ping signal. The format for sending data in Rose Real-Time is port_name.signal(data).send();

• The ping signal is defined in a protocol class and optionally may have data associated with them. Action code is below.

• talkRemote.ping().send();

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• This is the state diagram for the TCPClient capsule.

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• The transition for internalSetup sets a variable called internalFd which will be used by 'wakeup' calls to unblock the RTCustomController.

• internalFD is a internal UDP socket descriptor.

• UDP sockets are connectionless and have no protocol. There are suitable to use for the purpose of local host (board) communication.

• internalFd = makeUdpConnection();

Baltimore SIGAda• A connectionless service is one in which transmissions take place without a pre-established path between the source and destination. Because packets may arrive by different paths and in random sequences, there is no way to guarantee delivery of a message in a connectionless service. Because it can not guarantee delivery, a connectionless service is described as a best effort service.

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• The Action Code for the choice point labelled internalOK checks the value of internalFd [which is an internal socket descriptor] to see if if it has been set to a value other than -1 which it was initialized to.

• Action code is on next slide.

Baltimore SIGAda• if( internalFd < 0 )• return 0; // not OK• // Follow the FALSE path

• // of the Choice Point

• ioMonitor.add( internalFd, RTIOMonitor::CanRead );

• return 1; // OK• // Follow the TRUE path

• // of the Choice Point

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• TCPClient side transition action code for externalSetUp on next three slides

• The client will form connections actively to the TCPServer.

• The value of listening port has been set to 31736. This is the port number value of the NASAServer on this machine.

• The type of listening port is short int.

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• The RoseRT call to the log service will display the

• port number of the NASAServer• log.show("Connecting to: "); log.show( (int)LISTENING_PORT );

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If running on an embedded target, run either the server or client down on the embedded board. Run the other on your host machine. Modify the ip address defined in the TCPIP_Proxies::CONSTANTS to that of either the host or target. If both the server and client run on the same workstation the ip address can remain at 127.0.0.1.

• For the purposes of this demo MASTER_HOST is set to 127.0.0.1 because the client and server are running on the same microprocessor

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• if( c_socket.create() &&• c_socket.connect( (const char *)MASTER_HOST, (int)LISTENING_PORT ) )

• while( c_socket.state() == RTTcpSocket::SynSent )

• ioMonitor.wait( &RTTimespec::zero );

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• Action Code for Choice Point labelled external OK

• The function int RTTcpSocket::state() returns 'Established‘ if the socket file descriptor is usable

• return ( c_socket.state() == RTTcpSocket::Established );

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• if the state() function returns Established then the socket file descriptor is usable then take the TRUE path of the choice point which in this case is registerWithController

• if the state() function does not return Established then the socket file descriptor is not usable then take the FALSE path of the choice point which in this case is giveUP

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• Action Code for transition labelled giveUp

• Use the Rational Rose RT System Service called the Log Service to output a message without a carriage return

• log.show("IPC channel initialization failed\n");

• Close the external socket channel c_socket

• c_socket.close();

Baltimore SIGAda• Action Code for transition labeled registerWithController

• The macro REGISTER_LAYER takes three arguments which are pointers to the 'waitfunc', 'wakeupFunc', and 'processFunc‘ functions to be called by the RTCustomController.

• If any of these are null pointers the default values are used.

• The waitForEvents function is called when the when the RTCustomController does not have any messages left to deliver.

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• REGISTER_LAYER( waitForEvents, wakeup, 0);

• Use the Rational Rose RT System Service called the Log Service to output a message with a carriage return

• log.log("Connected");• set the length of the buffer to the integer value of the constant BUFFLEN which is in this 100

• buffLen = (int)BUFF_LEN;• talkRemote.recall();

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• This is the structure diagram for the TCPClient capsule.

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• The port labeled talkRemote is an public, conjugated, wired end port.

• Rational RoseReal-Time is a product of IBM Rational Software Corp.